diff --git a/lisp/Config.FreeBSD b/lisp/Config.FreeBSD
index 8d90dbc18b12745ab627a9361d7c6121776d7c79..f76630ba9d0a8257eeff6c2b1ae06d070021078f 100644
--- a/lisp/Config.FreeBSD
+++ b/lisp/Config.FreeBSD
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.FreeBSD_gencgc b/lisp/Config.FreeBSD_gencgc
index 86fe4e9417637f66fc9f3bdbb0d3b5511083da93..cb7263b0597517ef4ba83d073c36b8812c339041 100644
--- a/lisp/Config.FreeBSD_gencgc
+++ b/lisp/Config.FreeBSD_gencgc
@@ -6,9 +6,9 @@ CC = gcc
 LD = ld
 CPP = cpp
 ifneq (,$(filter 2% 3%, $(shell $(CC) -dumpversion)))
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 else
-CPPFLAGS = -iquote . -iquote $(PATH1) -I/usr/X11R6/include
+CPPFLAGS = -iquote . -iquote $(PATH1)
 endif
 CFLAGS = -Wstrict-prototypes -Wall -O2 -g -DGENCGC -DLINKAGE_TABLE
 ASFLAGS = -g -DGENCGC -DLINKAGE_TABLE
diff --git a/lisp/Config.NetBSD b/lisp/Config.NetBSD
index 230b71fd540f524e2cb8dafb5520e9a14ac24099..1cbffa7ddf04642560b9bfaa8b9dfb0f120f7b34 100644
--- a/lisp/Config.NetBSD
+++ b/lisp/Config.NetBSD
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.NetBSD_gencgc b/lisp/Config.NetBSD_gencgc
index 8836dbe05bbaf8bead537b48a53a436b376b40a8..aed1949f55680662f9e177382a4dc09b591c24e0 100644
--- a/lisp/Config.NetBSD_gencgc
+++ b/lisp/Config.NetBSD_gencgc
@@ -3,7 +3,7 @@ ARCH = $(shell uname -m)
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc -pipe
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.OpenBSD b/lisp/Config.OpenBSD
index dc59f41275ec0b66bbdc8e5df10ca38ebba180c3..f01549cd860c9b303829e4795b5bb79d2f17668a 100644
--- a/lisp/Config.OpenBSD
+++ b/lisp/Config.OpenBSD
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.OpenBSD_gencgc b/lisp/Config.OpenBSD_gencgc
index cf2b82df36de80ea6302ff7a5d959ee33e0e7450..d93bf1bcc20d7861d7f9f876244273493408c263 100644
--- a/lisp/Config.OpenBSD_gencgc
+++ b/lisp/Config.OpenBSD_gencgc
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.amd64 b/lisp/Config.amd64
index 82ae2c447ebb0c4f48a104e9e73501f03a25c01e..dc2b82eecaae3686d1aca1b9f426deefd320d2da 100644
--- a/lisp/Config.amd64
+++ b/lisp/Config.amd64
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.hp700_ux90 b/lisp/Config.hp700_ux90
index f06af46d0a737bf9bc022bd3cd5a6facc6a91dbb..20a2aed4c596c16908d4c7556fdd44e5034fb109 100644
--- a/lisp/Config.hp700_ux90
+++ b/lisp/Config.hp700_ux90
@@ -1,5 +1,5 @@
 CPPFLAGS = -Dparisc -I. -I/usr/cygnus/lib/gcc-lib/hppa1.1-hp-hpux9.05/2.6-95q3/include \
-	-I/usr/include -I/usr/include/X11R5
+	-I/usr/include
 LINK.o = gcc $(LDFLAGS) $(TARGET_ARCH)
 CC = gcc
 NM = hpux-nm
diff --git a/lisp/Config.linux b/lisp/Config.linux
index 72e0055c2dc03a5619b060f66122f730853c5508..5f7dbc6756d5dedbdbd3f72a93cdd5fe713d607e 100644
--- a/lisp/Config.linux
+++ b/lisp/Config.linux
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I- -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1) -I-
 CC = gcc -m32
 LD = ld
 CPP = cpp
diff --git a/lisp/Config.linux_gencgc b/lisp/Config.linux_gencgc
index 6e8ddb3da79615ab6b053b71b314145998ed6f9c..6c5cadf415eb1574ec88156aca818b4518af22b6 100644
--- a/lisp/Config.linux_gencgc
+++ b/lisp/Config.linux_gencgc
@@ -20,7 +20,7 @@ endif
 
 RUNTIME = $(GENCGC) $(LINKAGE)
 # __NO_CTYPE so builds on glibc 2.3 will run on (some) older glibc's.
-CPPFLAGS = -D__NO_CTYPE -D_GNU_SOURCE -I. -I$(PATH1) -I- -I/usr/X11R6/include $(RUNTIME)
+CPPFLAGS = -D__NO_CTYPE -D_GNU_SOURCE -I. -I$(PATH1) -I- $(RUNTIME)
 
 CFLAGS = -rdynamic -Wstrict-prototypes -Wall -O2 -g $(RUNTIME)
 ASFLAGS = -g $(GENCGC) $(LINKAGE_TABLE)
diff --git a/lisp/Config.parisc_mach b/lisp/Config.parisc_mach
index 40d3817ca11a6eca223a42bdd56b8614d7f492bf..cc66e6ff6ca6a48a93ae715de6ec9c889eb484aa 100644
--- a/lisp/Config.parisc_mach
+++ b/lisp/Config.parisc_mach
@@ -1,5 +1,5 @@
 CPPFLAGS = -Dparisc -Dhpux -DMACH \
-	-I. -I/usr/misc/.X11/include -I/usr/mach/include -Ihacks
+	-I. -I/usr/mach/include -Ihacks
 LINK.o = /usr/src/mach/bin/cc $(LDFLAGS) $(TARGET_ARCH)
 CC = /usr/src/mach/bin/cc
 NM = hacks/my-nm
diff --git a/lisp/Config.pmax_mach b/lisp/Config.pmax_mach
index da0e82a3593854ed20ec55e1ccd6982d0cb68d91..8b1caa31a54f57169c3703ed09dc3a4eeae0e26c 100644
--- a/lisp/Config.pmax_mach
+++ b/lisp/Config.pmax_mach
@@ -1,4 +1,4 @@
-CPPFLAGS = -I. -I/usr/misc/.X11/include -I/usr/mach/include
+CPPFLAGS = -I. -I/usr/mach/include
 CC = gcc # -Wall -Wstrict-prototypes -Wmissing-prototypes
 CPP = /usr/cs/lib/cpp
 CFLAGS = -O
diff --git a/lisp/Config.ppc_darwin b/lisp/Config.ppc_darwin
index decd700dd416c33ea7d780507067ee52a9644e0d..23d58c3bd46457cbd46beecd7ca94acac3fa9976 100644
--- a/lisp/Config.ppc_darwin
+++ b/lisp/Config.ppc_darwin
@@ -2,7 +2,7 @@ PATH1 = ../../src/lisp
 vpath %.h $(PATH1)
 vpath %.c $(PATH1)
 vpath %.S $(PATH1)
-CPPFLAGS = -I. -I$(PATH1) -I/usr/X11R6/include
+CPPFLAGS = -I. -I$(PATH1)
 # For Mac OS X 10.2, gcc3 is appropriate.  For 10.4, gcc (gcc 4.0) is ok.  But
 # this means -traditional is needed because gcc 4 seems to handle '##'
 # differently from gcc-3.3.  I (rtoy) don't know which is right, but I
diff --git a/lisp/Config.sun4_mach b/lisp/Config.sun4_mach
index 0b75a3ae2f90851ac6665c48de50ad24daa9ef3c..4e02ed9c93652666c2b95c99e4bbd7e23850b204 100644
--- a/lisp/Config.sun4_mach
+++ b/lisp/Config.sun4_mach
@@ -1,4 +1,4 @@
-CPPFLAGS = -I. -I/usr/misc/.X11/include
+CPPFLAGS = -I.
 CC = gcc # -Wall -Wstrict-prototypes -Wmissing-prototypes
 CPP = /usr/cs/lib/cpp
 CFLAGS = -g
diff --git a/lisp/Config.sun4_solaris_gcc b/lisp/Config.sun4_solaris_gcc
index 890e9138564d1221466656edf86c0e5d3623fc8f..8551860901b2d89deeec69256fbe6f3062009d6f 100644
--- a/lisp/Config.sun4_solaris_gcc
+++ b/lisp/Config.sun4_solaris_gcc
@@ -38,7 +38,7 @@ GENCGC = -DGENCGC
 GC_SRC = gencgc.c
 endif
 
-CPPFLAGS = -I. -I$(PATH1) -I/usr/openwin/include -I/usr/include/X11 -DSOLARIS -DSOLARIS25 -DSVR4 $(CC_V8PLUS) $(LINKAGE) $(GENCGC)
+CPPFLAGS = -I. -I$(PATH1) -DSOLARIS -DSOLARIS25 -DSVR4 $(CC_V8PLUS) $(LINKAGE) $(GENCGC)
 
 # Note: If you want to be able to run gdb with cmucl, the only version
 # of gdb that still works for me (rtoy) on Solaris is 4.18.  Versions
diff --git a/lisp/Config.sun4_solaris_sunc b/lisp/Config.sun4_solaris_sunc
index 427d9825d19656ddeb1dd76381116628b962ae19..6f14af52301b0c89b99f3bb1b99efefd6a751add 100644
--- a/lisp/Config.sun4_solaris_sunc
+++ b/lisp/Config.sun4_solaris_sunc
@@ -35,7 +35,7 @@ GENCGC = -DGENCGC
 GC_SRC = gencgc.c
 endif
 
-CPPFLAGS = -Dinline= -I. -I$(PATH1) -I/usr/openwin/include -I/usr/include/X11 -DSOLARIS -DSOLARIS25 -DSVR4 $(CC_V8PLUS) $(LINKAGE) $(GENCGC)
+CPPFLAGS = -Dinline= -I. -I$(PATH1) -DSOLARIS -DSOLARIS25 -DSVR4 $(CC_V8PLUS) $(LINKAGE) $(GENCGC)
 
 
 CC = cc -O -xlibmieee
diff --git a/lisp/Config.sun4c_41 b/lisp/Config.sun4c_41
index cee9f47f44bda7eb27ad1d16f846d6db88d136e3..50e23256ffce4b8479a462c4362f9504ae71b17d 100644
--- a/lisp/Config.sun4c_41
+++ b/lisp/Config.sun4c_41
@@ -1,4 +1,4 @@
-CPPFLAGS = -I. -I/usr/misc/.X11/include -DSUNOS
+CPPFLAGS = -I. -DSUNOS
 CC = gcc # -Wall -Wstrict-prototypes -Wmissing-prototypes
 CPP = /lib/cpp
 CFLAGS = -O